This investigation addresses the need to define the neural circuit mechanisms by which ethanol disrupts higher-order selective sensory processing in primary and associative areas of the cerebral cortex. As neurophysiological models for such processing, the PI has described several types of sensory modulation in the somatosensory cortex of rats. These include: 1) inhibitory sensory "gating" occurring in phase with forelimb movement, 2) sensory facilitation occurring in arousal, and 3) sensory facilitation occurring in attention and anticipation behaviors. All these phenomena will be investigated using a technique the PI has developed for simultaneous recording from multiple single neurons through arrays of microwire electrodes chronically implanted in precise locations the cortex and thalamus. The major aim will be to test the effects of ethanol on normal circuit interactions exhibited in these recordings. Also, the long term stability of such recordings will allow the same neurons to be recorded over the time course of ethanol chronicity and withdrawal, and over administrations of other drugs of abuse. Finally, genetic models (such as P-NP rats) will be used.